Saturday, April 11, 2015

Understanding Windows DNS Forward Lookup Zones

Though I have been setting up domain controllers for years and years, I am still a relative newbie when it comes to understanding Microsoft Windows DNS, therefore, I thought it would be worthwhile to clarify some aspects of how Windows DNS works.

For the purposes of this article, we will basically be discussing only A and CNAME Records. So, an A Record simply identifies a server with its IP Address. A CNAME Record identifies a particular name with a particular server.

For example, a server called MyServer would have an A Record pointing to an IP Address of 10.0.0.10.

A CNAME Record would point the name DevServer to the MyServer A Record.

Well, now what is the purpose of a Forward Lookup Zone?

By default, Windows DNS will create a Forward Lookup Zone based on the domain that you have created and set up.

So, if you have a domain called mycorpdomain.com, your default Forward Lookup Zone would be also called mycorpdomain.com.

What this means is that all of your A and CNAME records will ultimately end in the suffix: mycorpdomain.com.

But what if you want to have a different suffix such as dev.mycorpdomain.com? Well, that is where Forward Lookup Zones come in!!

You can create an additional Forward Lookup Zone called dev.mycorpdomain.com. Beneath that new Forward Lookup Zone, you can then subsequently create corresponding A and CNAME records to point to your existing MyServer member server.

Therefore, once you have your new Forward Lookup Zone in place, you will be able to access MyServer by multiple Urls (in the case of a web server):

myserver.mycorpdomain.com

myserver.dev.mycorpdomain.com

This comes in very handy particularly when you want to delineate your environments. Therefore, you could have various Forward Lookup Zones for dev.mycorpdomain.com, qa.mycorpdomain.com, staging.mycorpdomain.com, prod.mycorpdomain.com and so on.

That is pretty much all there is to understanding Forward Lookup Zones with Windows DNS!!